When I'm doing regular revision, sure it's okay... but I will use questions from my own books because they are not exactly the perfect HSC style + I want to get the best use out of these books that I've bought. When I use up these resources, I will then turn to HSC questions and by then I am doing full papers and order doesn't really matter. I don't want to focus one topic more than another, since they are all effectively equal in the exam.